Tunnels under Trafalgar Square

With its plinths, fountains, the imposing facade of the National Gallery, and of course Nelson's Column, Trafalgar Square looks solid and stately. However, beneath its paving and pools, empty tunnels snake unseen. 

These tunnels were dug during the construction of the Jubilee Line, whose Charing Cross station opened in 1979. Used to transport spoil and materials, they ran from the station at the south-east of the square, up to the north-west corner where the National Gallery's Sainsbury Wing now stands. 

The far end is now blocked off, ending roughly underneath the fourth plinth (the former empty plinth, now used for temporary displays). 

Cast iron plates line the tunnels. Each bears its year: evidence that some were reused from earlier projects. 

There's a noticeable curve to the tunnel. It's not a navigation error on the part of the builders, but a deliberate detour to avoid Nelson's Column. 

These aren't the only tunnels at the station which the public don't see. Another set are used to ventilate it: the grilles allow those within to observe passing people...

... and passing trains. 

At the end, a ventilation shaft reaches up to the surface and far down below our feet. 

It's an extraordinary look behind the scenes: part of the Hidden London programme from the London Transport Museum. The Charing Cross tour combines these tunnels with a visit to the disused Jubilee Line platforms. Booking is open for the forthcoming season, including visits to Clapham South Deep Level Shelter and poster-lined abandoned tunnels in Euston Station. 

Hidden Charing Cross Station

In 1999, the Jubilee Line was extended to Stratford, via the soon-to-open Millennium Dome. However, south and east London's gain was Charing Cross's loss: formerly the terminal station for the line, it was now bypassed altogether. Instead, the Jubilee line south of Green Park diverted to Westminster and beyond. 

The result: two platforms of Charing Cross underground station were closed. However, that doesn't mean that they are abandoned. On the contrary, their disused status has allowed them to serve three new functions. First, they are used as sidings and stabling for the extended Jubilee line, and for ventilation: useful, but not very exciting. They are use for much more than that, though. 

Second, the former Jubilee Line station is a popular location for filming. If you want a fairly modern tube station, with escalators and all the rest but without those pesky passengers, Charing Cross is probably your location of choice. Visitors have ranged from James Bond to Paddington - and they've left some subtle traces. 

You'd have to do a lot of circuits of this station to find the District and Circle lines, since they actually run through nearby Embankment Station. The signage is left from filming of Skyfall, where it served as a (somewhat inaccurate) stand-in for Temple Station. (The 'stand on the right' signs were also removed from the escalators to avoid injury during the chase scene.)

Art of Lies is nowhere to be found on IMDB, and won't be in cinemas near you. 

And if you want to sign up to this 'fiber optic' broadband provider, think again: there are no contact details. These are filming artefacts: as showing real posters on screen can cause copyright issues, some have been replaced by generic mock-adverts instead.  

Even the famous roundel has been remodelled for one event!

Finally, the platforms are used to test proposed innovations. Some have since been extended across the network, such as raised platform 'bumps' for step-free access. Others, like these glow-strips near platform ages, have not made it further than Charing Cross.

We might add a fourth use: tours of these platforms are a popular part of London Transport Museum's Hidden London programme. Booking for the next season is about to start, and includes Clapham South Deep Level Shelter and abandoned tunnels at Euston. 

Clerkenwell Old Sessions House

In 1782, the Middlesex Quarter Sessions House on Clerkenwell Green opened. It replaced the courts' earlier home on St John Street, Hicks Hall, which had become too small and decrepit. The new location was also more suitable for solemn proceedings: the old site was on the path of livestock heading into Smithfield Market, with all the noise and congestion they produced. 

The quarter sessions was the predecessor of today's crown courts, hearing criminal cases too serious for a single magistrate to deal with (although the most serious were reserved for the assizes courts). Quarter sessions cases were heard by a panel of three magistrates and a jury. So keen were the magistrates to build a suitable home for these proceedings that they adopted an unnecessarily convoluted process for its design. They first considered plans drawn up by the county surveyor, Thomas Rogers, and rejected them. They then heard Rogers' request for the design job, and rejected it. Instead, they held a competition; eleven entries were submitted, and they chose one by ... Thomas Rogers. Once his building was completed - somewhat altered from the original design, since the magistrates kept interfering - cases would be heard in its grand surroundings for over a century. 

The heart of the building is its central hall, rising the full height of its two original floors and topped by a dome. Behind it, reached by the sweeping staircase, was the courtroom itself. The pillars are original, but the screen between them was added when the magistrates discovered such 'open justice' resulted in poor acoustics. 

This double flight of stairs was another alteration made by the magistrates. Originally, rather tighter and more modest staircases were planned - they were reused instead as back stairs. 

The sessions house was remodelled in the nineteenth century, partly in the hope of improving poor lighting and ventilation. Extra court space was also needed as the area served became more populous, and the magistrates' dining room was converted into a second courtroom. 

Further height was added to the building to accommodate an additional floor, complete with new dining room. The hall was also remodelled, giving extra balcony space to cope with the number of people using it. 

Such provision of extra court space must have been timely: a few years later, in 1868, the Metropolitan railway opened at the building's feet, with Farringdon station a short walk away. Clerkenwell Road was built soon after, freeing up some space in the process which was used for an extension to the Sessions House. 

However, its fortunes changed when the County of London was created in 1889. They took over both Clerkenwell and the sessions house at Newington; to save money, they decided to use only the Newington site and sell Clerkenwell. The court moved out of the building in 1921. Ten years later, it took on a very different role as Avery Scales moved in. (They used it as their headquarters, not for manufacturing weighing equipment!) After the weighing machine manufacturers left in the 1970s, the building became a masonic lodge for a while.  

The Sessions House is about to begin a new life as a food venue and restaurant, but there was a chance to enjoy its faded glories during Fashion Week, when it hosted Burberry's photography exhibition Here We Are.